Shear seals have been known and used for a long time. The traditional shear seals have been reasonably effective in accomplishing their intended function of permitting one member to rotate relative to another to a limited degree while still effecting a seal between the opposite sides of the shear seal.
U.S. Pat. No. 3,680,924 to Robert J. Otto et al, issued Aug. 1, 1972, shows a shear seal for a track pin of an endless track wherein an inner metal ring of the seal is pressed or cemented to one link and the outer metal ring is pressed or cemented to the other link with an elastomeric ring bonded between the metal rings. To gain access to the bearing requires that the elastomeric ring be destroyed in order to remove the shear seal from its mounting. In addition, the relative tolerances between the metal rings and their mating surfaces must be closely controlled.
U.S. Pat. No. 3,218,107 to H. L. Reinsma, issued Nov. 16, 1965, shows a shear seal having an inner sleeve and an outer sleeve joined by an elastomeric ring. The sleeves are press fitted onto a pin and into a link, respectively, not only to provide a seal, but also to permit limited relative rotation between the pin and the link. On occasion when it is necessary to remove the shear seal, it is more than likely that the shear seal will be damaged or destroyed in order to remove it from its press fit seats. Once again, the relative tolerances between the sleeves and their mating surfaces must be closely controlled.